We really need to be able to do something with Pokémon that just sit in boxes.

In PokéRanch we could at least watch them run around and interact.
In Sun/Moon we had Poké Pelago.
In Sword/Shield we had Poké Jobs.
In Legends Arceus, we have Pastures
In Scarlet/Violet we have... nothing
In Legends Z-A we have nothing again

So, why keep unused Pokémon in the game and not just shove them in Pokémon Home, or just do an endless wondertrade cycle? It seems like there's really no point in keeping Pokémon in a game now unless you're using them in battle, or using them to breed.